The present invention relates to a dental implant system and a method for its manufacture. More precisely, the invention concerns a system, by means of which a highly permanent and precise removable prosthesis can be created, especially for a patient's mandible.
Implant treatment, as such, has been known for decades. In general, an implant refers to a screw or cylinder permanently set in a hole drilled in the patient's mandible or maxilla, which can support various prosthetic structures. The screw or cylinder is nearly always made from titanium.
When it is wished to construct a removable full mandible prosthesis on implants, it has usually been carried out until now by first of all setting the implant screws in place in the mandible. Once the screws have become firmly osteointegrated (i.e. ossified) in the mandible, extensions penetrating the gum (mucous membrane inserts) are screwed into them. Attachment is by means of the conical upper surface of the implant fitting a conical counter surface in the extension. However, implants are also used, in which there is a shoulder joint surface and a corresponding shoulder joint surface in the extension. Implants are also used, which themselves penetrate the gum (i.e. gingiva). A bar is constructed on the part above the gum and the prosthesis is attached by suitable means, such as a snap-fastener (riders) or attachments.
This is only an approximate description of the procedure, because in practice modern systems contain tens, if not hundreds of different parts. Though these are naturally intended to create an optimal solution for each case, the large number of parts is a nuisance to both the manufacture and the dentist.
Another serious drawback of the known structures is the difficulty of creating a good fit between the adjustment surfaces described above. In itself, it is easy to create as good fit using conical or shoulder connection surfaces, but if the same assembly contains several joints formed by conical connection surfaces, adjustment becomes extremely difficult. Conical connection surfaces are very difficult, as it is awkward to create a good fit in more than one joint between a screw and an extension and then between the extension and the bar. Thus, in known systems, a great deal of attention must be paid to the parallelism of the implants.
Another problem with conical fitting joints is that because certain movement tolerances are used relative to the parts to be joined, known systems often have connections in which steps are formed in the connection surface. Such steps form areas in the prosthetic system that irritate tissue and induce bacterial growth.
The present invention contemplates a new and improved apparatus and method which overcomes the above-referenced problems and others.